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Archive 2013 · Is there something wrong with this Lux 50 ASPH?
  
 
turnstyle
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p.1 #1 · p.1 #1 · Is there something wrong with this Lux 50 ASPH?


Hi all, I'd be very grateful if you might have a sec to take a look at the test images below -- I'm trying to figure out if a new Lux 50 ASPH is working as expected. It's mounted on a Sony NEX7 with a Voightlander M to E adapter.

I shot some uniform subjects at an angle, with the expectation that something should be in focus across the frame. What I see: sharp in the center, mushier out to the sides. And the left side seems mushier than the right.

I'm not 100% sure exactly what I should expect to see -- so I'd be very grateful if any of you can check these out and let me know what you think. (Each is 6000x4000, and about 5MB.)

Or, if I should a different test, please let me know!

http://turnstyle.com/lux50/DSC05947.jpg

http://turnstyle.com/lux50/DSC05949.jpg

http://turnstyle.com/lux50/DSC05994.jpg

http://turnstyle.com/lux50/DSC05995.jpg

Thanks very kindly!



Nov 02, 2013 at 09:22 PM
Mescalamba
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p.1 #2 · p.1 #2 · Is there something wrong with this Lux 50 ASPH?


Well, adapters do have effect on lens performance. NEX-7 is famous for being rangefinder lens un-friendly (I think I see very small color shift even). All summed up, I think its normal.

Those images are shot most likely somewhere around MFD, arent they? Usually not strong point of any fast normal lens..



Nov 02, 2013 at 09:39 PM
turnstyle
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p.1 #3 · p.1 #3 · Is there something wrong with this Lux 50 ASPH?


Thank you!

I was close, but not minimum -- roughly how far would be appropriate for a test of this lens?

Can you recommend any documents that explain how to adjust the screws on the adapter to make sure the lens/adapter/camera is optimally configured?

I really appreciate any/all comments!



Nov 02, 2013 at 09:46 PM
Taylor Sherman
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p.1 #4 · p.1 #4 · Is there something wrong with this Lux 50 ASPH?


Are those at f/1.4? look at the MTFs for this lens ("Technical Data" link on the right side of this page: http://us.leica-camera.com/photography/m_system/lenses/2183.html). ON the Nex-7, the side edges correspond to about the 12mm mark, exactly where the dip in the 40 lp/mm line is. It's a weak spot of the lens at that aperture. But, not that the lens is that bad at f/1.4 compared to many others. And looking at 100% shots on the Nex-7 is a pretty tough critique for any lens.

As for one side being better or worse, that could be the adapter being slightly off-center.

Otherwise, looks fine.



Nov 02, 2013 at 09:48 PM
Mescalamba
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p.1 #5 · p.1 #5 · Is there something wrong with this Lux 50 ASPH?


Dunno, if you have same adapter as once I had, but that M one I had from Voigtlaender was a bit "wobbly". If your is completely firm, then its good. Not sure there is any way to tweak shift/tilt. Would be nice if there was.

NEX-7 pixel density is 2.3x more than M-240 and that really is a lot of difference, so lens might not be soo perfect as you would expect. There isnt perfect lens anyway. Plus obviously it shows any inaccuracy in adapter..



Nov 02, 2013 at 10:05 PM
turnstyle
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p.1 #6 · p.1 #6 · Is there something wrong with this Lux 50 ASPH?


The Voigtlander adapter doesn't seem wobbly to me, at least I haven't noticed anything. I think it has a few screws that can adjust the distance -- but I'm not exactly sure how to smartly go about it.

One more question: the NEX7 is effectively cropping the image from the Lux, right? So the sides in these shots are really the mids of the lens? I hope that made sense -- eg, I'm curious how the MTF applies to a cropped sensor.

Meaning: looking at the MTF, am I seeing that big dip at the side of my NEX -- but on A7 or A7r, it would get sharper again, then fall back off?

Again, thanks kindly!



Nov 02, 2013 at 10:18 PM
Taylor Sherman
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p.1 #7 · p.1 #7 · Is there something wrong with this Lux 50 ASPH?


Correct.



Nov 02, 2013 at 11:53 PM
adamdewilde
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p.1 #8 · p.1 #8 · Is there something wrong with this Lux 50 ASPH?


NOPE, not normal. It is possibly the adapter. Any other lenses doing it to this degree?
If not, the lens is wonky.



Nov 03, 2013 at 08:29 PM
turnstyle
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p.1 #9 · p.1 #9 · Is there something wrong with this Lux 50 ASPH?


From what I can tell, I think the adapter is focusing a bit past infinity -- and from what I now understand, that may adversely affect focus ability overall -- and I gather there may not be a way to adjust the adapter (I got one from Voightlander) -- so, I'm trying to figure out best next steps. I might try getting another adapter to see if I hit infinity at infinity, not sure, yikes.



Nov 03, 2013 at 11:49 PM
LightShow
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p.1 #10 · p.1 #10 · Is there something wrong with this Lux 50 ASPH?


With floating elements, incorrect registration distance could cause image degradation.
Go to the hardware store and get a micrometer/calipers, then you can measure your adapters to see how in spec and uniform each is, then you can go about and shim if required.



Nov 04, 2013 at 02:39 AM
 

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zhangyue
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p.1 #11 · p.1 #11 · Is there something wrong with this Lux 50 ASPH?




turnstyle wrote:
From what I can tell, I think the adapter is focusing a bit past infinity -- and from what I now understand, that may adversely affect focus ability overall -- and I gather there may not be a way to adjust the adapter (I got one from Voightlander) -- so, I'm trying to figure out best next steps. I might try getting another adapter to see if I hit infinity at infinity, not sure, yikes.


My lux always slightly past infinity on M9. I think that is normal. You might need more data point to make this valid.



Nov 04, 2013 at 03:15 AM
sebboh
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p.1 #12 · p.1 #12 · Is there something wrong with this Lux 50 ASPH?


zhangyue wrote:
My lux always slightly past infinity on M9. I think that is normal. You might need more data point to make this valid.


do you mean it focuses past the infinity mark on the lens even after leica fixed it or do you mean that infinity on the lens doesn't correspond to actual infinity focus?




Nov 04, 2013 at 03:36 AM
charles.K
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p.1 #13 · p.1 #13 · Is there something wrong with this Lux 50 ASPH?


I have had 3 Lux's, and any one that focused past infinity was sent back to be recalibrated and CLA'd.

The edges where there should be sharp are distorted, in the plane of focus.

I would suggest this is not normal



Nov 04, 2013 at 03:46 AM
sebboh
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p.1 #14 · p.1 #14 · Is there something wrong with this Lux 50 ASPH?


charles.K wrote:
The edges where there should be sharp are distorted, in the plane of focus.

I would suggest this is not normal


remember this is on aps-c where the lux's midzone dip occurs on the edge instead of in the midzone, and of course lack of sharpness is magnified by the crop.




Nov 04, 2013 at 03:54 AM
zhangyue
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p.1 #15 · p.1 #15 · Is there something wrong with this Lux 50 ASPH?


sebboh wrote:
do you mean it focuses past the infinity mark on the lens even after leica fixed it or do you mean that infinity on the lens doesn't correspond to actual infinity focus?



The infinity mark on lens doesn't correspond to actual infinity focus but slightly pass infinity. Before the adjust I have this problem along with other at different distance. Now, after adjust by Leica , it seems spot on from 0.5 to 5M for me. but at infinity, I always to achieve better focus by pulling back a very small amount. (half mm or so) From end results, it seems a great performer.

Again, that is why I complain this lens so many times, Leica's design choice seems very risky. But if you don't pix PP it, which I don't usually it really doesn't matter until you thought about you deserve best by paying $4000.




Nov 04, 2013 at 04:10 AM
adamdewilde
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p.1 #16 · p.1 #16 · Is there something wrong with this Lux 50 ASPH?


zhangyue, don't buy the 50APO, mine focuses past infinity as well (slight bit) other functions seem normal, other then the flare issue, but we'll see how that turns out when I get my lens back.

My 50Lux doesn't have the focus past infinity problem.. Also sebboh, even with the MTF chart dip (I have no idea how to read MTF data), if I look at his leaves photo, that's not normal. If I shoot a textured object wide open, there's a straight sharp line across the whole frame with no softness (or at least none like what the OP is getting).

Depending on the angle and focusing distance, sometimes the line has a slight bend to it. One would have to actually run the test a bunch of times at different angles n focal distances to find the difference, and I've never really bothered doing that.



Nov 04, 2013 at 04:28 AM
sebboh
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p.1 #17 · p.1 #17 · Is there something wrong with this Lux 50 ASPH?


adamdewilde wrote:
My 50Lux doesn't have the focus past infinity problem.. Also sebboh, even with the MTF chart dip (I have no idea how to read MTF data), if I look at his leaves photo, that's not normal. If I shoot a textured object wide open, there's a straight sharp line across the whole frame with no softness (or at least none like what the OP is getting).

Depending on the angle and focusing distance, sometimes the line has a slight bend to it. One would have to actually run the test a bunch of times at different angles n focal distances
...Show more

i've certainly seen evidence of the midzone dip in the form of unsharpness in m9 shots with the lens, but i've never really looked at images of this type at this focal distance, so i'm not really sure what to expect, especially given that it's a 56mp sensor (if it were FF) and the adapter is too short throwing the floating element off slightly.

i'd try and find somebody with an m body to test the lens on to decide whether it's up to spec.




Nov 04, 2013 at 04:40 AM
turnstyle
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p.1 #18 · p.1 #18 · Is there something wrong with this Lux 50 ASPH?


Hi all, thanks for looking, and helping me understand.

Just to be clear: when I talk about infinity, I'm talking about rotating the lens to the hard stop (not about where the infinity symbol appears to be on the lens).

And thanks for the comment about the leaves photo -- my thinking was that with an angled shot, I should be able to see *something* in focus from left to right.

So now it seems like one of the following:

1) The adapter needs to be shimmed, so that the hard stop at infinity is focusing on infinity -- and this may improve focus performance.

2) Perhaps I'm just seeing the mid-frame fall-off, which is a characteristic of the lens.

3) Perhaps there is actually something wrong with the lens rather than the adapter (unfortunately I don't have a Leica body)

So, I'm still in a bit of a pickle -- but I feel like I'm, er, focusing in on the problem...



Nov 04, 2013 at 12:28 PM
adamdewilde
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p.1 #19 · p.1 #19 · Is there something wrong with this Lux 50 ASPH?


sebboh wrote:
i've certainly seen evidence of the midzone dip in the form of unsharpness in m9 shots with the lens, but i've never really looked at images of this type at this focal distance, so i'm not really sure what to expect, especially given that it's a 56mp sensor (if it were FF) and the adapter is too short throwing the floating element off slightly.

i'd try and find somebody with an m body to test the lens on to decide whether it's up to spec.



I agree, find someone with an M camera.. I think there's quite a bit of field curvature, but his images don't mirror mine performance wise, which is why I think something's off..



Nov 04, 2013 at 03:45 PM
rscheffler
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p.1 #20 · p.1 #20 · Is there something wrong with this Lux 50 ASPH?


I don't think it's so much of an adapter problem, at least not one causing one side to go softer than the other because the image characteristics seen in the plane of focus on one side is pretty much the same as seen on the other side.

I'm kind of leaning towards the mid zone dip corresponding to the APS-C frame edge thinking, combined with possibly slight blurring caused by the sensor toppings at the image edges.

Michael Reichmann did a test a while ago that was somewhat controversial for his methodology, but should offer some insight into the results you're getting. Continue down the page until you see the 100% crops. What MR did was a direct comparison of the 50 Lux ASPH on the NEX-7 and M9, cropping the M9 frame to the same angle of view as the NEX, then equalizing the file size for each. What this shows us is the difference in APS-C edge crop performance from each camera. IMO, the f/1.4 edge crop from the NEX look softer than the M9. While both images should suffer equally from the lens's mid zone dip at the edge of the APS-C crop, the NEX image definitely looks worse. Unless I'm missing something, it's my inclination to chalk this up to the difference in sensor toppings. NEX-7 with AA filter and probably fairly thick cover glass, vs. M9 with no AA and thin cover glass...



Nov 04, 2013 at 05:44 PM
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